Method and apparatus for generating electricity and storing energy using a thermal or nuclear power plant

ABSTRACT

A method for generating electricity by means of a nuclear power plant and a liquid vaporization apparatus involves, during a first period, producing heat energy by means of the nuclear power plant and using the heat energy to vaporize water or to heat water vapour, expanding the water vapour formed in a first turbine and using the first turbine to drive an electricity generator in order to produce electricity, vaporizing liquefied gas coming from a cryogenic store in order to produce pressurized gas, reheating the pressurized gas with a part of the water vapour intended for the first turbine of the nuclear power plant and expanding the pressurized fluid in a second turbine to produce electricity and, during the second period, liquefying the gas to be vaporized.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a §371 of International PCT ApplicationPCT/FR2014/053390, filed Dec. 17, 2014, which claims the benefit ofFR1363248, filed Dec. 20, 2013, both of which are herein incorporated byreference in their entireties.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a method and apparatus for thegeneration of electricity using a thermal or nuclear power plant whichpermits the storage of energy by the liquefaction of gas. The inventionalso relates to apparatus for the implementation of such methods.

A first object of the invention is the generation of electricity withimproved efficiency.

A second object of the invention is the reduction of storage costs forenergy generated by an electricity generation method using a power plantand incorporating an electrical energy storage facility using liquefiedgas.

BACKGROUND OF THE INVENTION

Many nuclear power plants are pressurized water reactors.

These nuclear power plants comprise at least two mutually independentwater circuits: the primary circuit and the secondary circuit.

The function of the primary circuit is the capture of heat from thenuclear reaction. Heat is produced in very large quantities by thefission of uranium atoms.

Placed within the reactor vessel, water in the primary circuit thusachieves a temperature of approximately 320°, after having been heatedduring the chain reaction.

This water does not boil, as it is very highly pressurized. It is thenrouted from the reactor core to the primary circuit, which is a closedcircuit.

The water in the primary circuit heats the water in the secondarycircuit via a steam generator, which permits the exchange of heatbetween the two independent circuits. The pipes in the primary circuitheat the water in the secondary circuit by contact to form water vapor.

The water in the secondary circuit is at a lower pressure, and istherefore converted into steam. This steam drives the reactor turbine.The rotation of the turbine in turn drives the generator, thuspermitting the production of electricity.

Other nuclear power plants have a primary circuit only, and the waterwhich is heated by the nuclear reaction is vaporized to form watervapor.

US-A-2012151961 describes a method for the storage of liquefied air.During phases of low electricity demand, air is liquefied and stored.During phases of high electricity demand, liquid air is vaporized in asystem which optimizes the recovery of cold, to generate a pressurizedfluid which drives a turbine for the production of electricity. Theenergy obtained (and consequently the efficiency of storage) is all themore efficient if the fluid is heated using residual heat prior toexpansion.

The article “Cryogenic Solutions for Energy Storage and the Optimizationof Energy Supply” in the Revue Générale du Froid, by Dubettier et al,describes the heating of vaporized air using residual heat, or by meansof natural gas burners to increase the energy produced by the expansionof air.

The solution described in the prior art is as follows:

-   -   during phases of low demand:        -   Electrical energy is used to produce liquid air        -   A proportion of the available thermal energy is stored for            use at times of high demand, and will be used to heat up            pressurized gas prior to expansion    -   and during phases of high demand:        -   Liquefied gas is vaporized, with the recovery of cold, to            produce a pressurized gas        -   The pressurized gas is heated using previously stored            thermal energy        -   The gas is expanded to produce electricity

SUMMARY OF THE INVENTION

In a thermal power plant, hot gases generated by the combustion of fuel(coal, natural gas, oil, etc.) heat the water or water vapor to formwater vapor which is to be fed to a steam turbine, which generateselectricity. The same applies in a combined cycle where the combustiongases which expand in the gas turbine, and are still hot, are used toheat the water or water vapor to form water vapor which is to be fed asteam turbine, which generates electricity.

It is surprising to observe that the generation of electricity is moreefficient where a proportion of the heat generated by the power plant isused, not in the steam turbine of the power plant, but for thepreheating of a gas which is to be fed to a turbine.

Rather than storing thermal energy during phases of low demand, it isproposed that a proportion of the thermal energy produced by the powerplant during phases of high demand should be tapped: this reduceselectricity production by the thermal power plant, but permits asubstantial increase in the electrical energy produced by thepressurized fluid, which has been heated by the thermal energy thustapped.

Although the energy efficiency performance is slightly impaired in thiscase, investment in a very large-scale and highly expensive thermalenergy storage facility can be obviated.

One object of the invention is the reduction of the cost of anelectricity generating apparatus by eliminating the requirement forstorage facilities.

According to certain embodiments of the invention, primary (rather thanresidual) thermal energy is used, which is normally employed for thegeneration of electricity in the power plant, at the time, moreover,where electricity is to be supplied to the grid system. The superiorefficiency of the vaporized air (or atmospheric gas) cycle, incomparison with the steam cycle of the steam turbine of the power plant,is exploited to deliver more energy to the grid system.

During periods of low electricity consumption, it is sometimes necessaryto store thermal energy generated by the power plant. Thermal energystorage facilities required for this purpose are voluminous, expensiveand relatively difficult to implement.

In one embodiment, the invention proposes the elimination or reductionin size of these storage facilities, and the replacement thereof, atleast partially, by a system for the liquefaction of air or ofatmospheric gas.

According to one object of the invention, a method is proposed for thegeneration of electricity and the storage of energy by means of athermal power plant or a nuclear power plant, and a liquid vaporizationapparatus, wherein

A) during a first period:

a) i) thermal energy is produced by means of the thermal power plant,gases are produced, at least a proportion of the gases is used tovaporize water or to heat water vapor, the water vapor formed isexpanded in a first turbine, and the first turbine is used to drive anelectricity generator for the production of electricity

-   -   or        -   ii) thermal energy is produced by means of the nuclear power            plant, and the thermal energy is used to vaporize water or            to heat water vapor, the water vapor formed is expanded in a            first turbine, and the first turbine is used to drive an            electricity generator for the production of electricity    -   b) liquefied gas sourced from a cryogenic storage facility is        vaporized to produce a pressurized gas    -   c) the pressurized gas is heated, and    -   d) the pressurized fluid is expanded in a second turbine for the        production of electricity    -   e) to heat the pressurized fluid, a proportion of the thermal        energy produced in step a) is used for the heating of the        pressurized fluid, by employing a proportion of the gases from        the thermal power plant or a proportion of the water vapor to be        delivered to the first turbine of the thermal or nuclear power        plant, or a proportion of the heat of the water vapor to be        delivered to the first turbine of the thermal or nuclear power        plant for the heating of the pressurized fluid, and    -   B) during a second period    -   a′) thermal energy is produced by means of the thermal or        nuclear power plant, and the thermal energy is used to generate        electricity,    -   b′) electrical and/or mechanical energy generated by the power        plant is used to liquefy the gas, and    -   c′) the liquefied gas is stored in a storage facility (S).

According to further optional aspects:

-   -   thermal energy is produced by means of a nuclear power plant, a        fluid is heated by the heat generated by a nuclear reaction, a        proportion of the heat energy of the heated fluid is used to        preheat the fluid to be delivered to the second turbine, and a        further proportion of the heat energy of the heated fluid is        used to heat the water or water vapor delivered to a first        turbine, where its expansion generates electricity.    -   a first proportion of the fluid heated by the nuclear reaction        heats the water or water vapor to be delivered to the first        turbine, and a second proportion of the fluid heated by the        nuclear reaction heats the pressurized gas to be delivered to        the second turbine, whereby the flow rate of the second        proportion of the fluid is no more than 30% of the sum of the        first and second proportions.    -   a first proportion of the water vapor generated by the nuclear        reaction expands in the first turbine, and a second proportion        of the water vapor generated by the nuclear reaction is used to        preheat the pressurized gas to be delivered to the second        turbine, whereby the flow rate of the second proportion of the        water vapor is no more than 30% of the sum of the first and        second proportions.    -   thermal energy is produced by means of a thermal power plant,        gases are produced by the combustion of a fuel, a proportion of        the heat of th gases is used to preheat the fluid to be        delivered to the second turbine, and a further proportion of the        heat of the gases is used to heat the water or water vapor        delivered to a first turbine, where its expansion generates        electricity.    -   a first proportion of the gases is used to heat the steam        delivered to the first turbine for expansion, and a second        proportion of the gases preheats the pressurized gas, whereby        the flow rate of the second proportion of the gases is no more        than 30% of the sum of the first and second proportions.    -   the gases firstly heat the pressurized gas, and are then used to        heat the steam which is delivered to the first turbine, where it        expands.    -   the first and second turbines in combination produce more        electricity than would have been produced by the first turbine        alone, using all the heat energy of the heated fluid or the        gases respectively to heat the water or water vapor to be        delivered to the first turbine.    -   the electricity generated by the first and/or second turbine is        transmitted to the grid system.    -   the only gas which expands in the second turbine is the        pressurized fluid.    -   during the first period, the gas is not liquefied.    -   the second period corresponds to a period of lower electricity        demand and/or a period in which the electricity tariff is lower        than in the first period.    -   during the second period, the first turbine generates        electricity, which is used to liquefy the gas.    -   during the first period, the gas is not liquefied.    -   during the first period, the stored liquid is not vaporized        and/or the pressurized fluid is not expanded in the second        turbine.

According to a further object of the invention, an integratedelectricity generating apparatus is provided, comprising a nuclear orthermal power plant with a first turbine, which is a steam turbine,connected to means for the generation of electricity, an apparatus forthe liquefaction of a gas and the vaporization of the liquefied gas witha second turbine, which is a turbine for the expansion of vaporizedliquefied gas, connected to means for the generation of electricity,means for the transference of electrical or mechanical energy from thepower plant to the liquefaction apparatus, and means for the preheatingof the vaporized liquefied gas up-circuit of the expansion turbine,characterized in that it comprises means for the transmission

-   -   i) of the gases or water vapor, originating from the thermal        power plant, or    -   ii) of the water vapor generated and/or heated by the nuclear        reaction, and originating from the nuclear power plant, or    -   iii) of a fluid heated by the nuclear reaction, originating from        the nuclear power plant, to the means for the preheating of the        vaporized liquefied gas, in that the liquefaction apparatus is        connected to the power plant for the supply thereto of        electrical and/or mechanical energy generated by the power        plant, and in that it comprises a storage facility for the        storage of liquefied gas.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, claims, and accompanying drawings. It is to be noted,however, that the drawings illustrate only several embodiments of theinvention and are therefore not to be considered limiting of theinvention's scope as it can admit to other equally effectiveembodiments.

FIG. 1 represents a process flow diagram in accordance with anembodiment of the present invention.

FIG. 2 represents a process flow diagram in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION

The invention will be described in greater detail with reference to thefigures, which illustrate a method according to the invention. FIG. 1shows a schematic and partial representation of a method according tothe invention, and FIG. 2 shows the details of one variant of a methodaccording to the invention.

In FIG. 1, for the implementation of a method for the generation ofelectricity, a power plant 3 is used, which may be a thermal power plantor a nuclear power plant, together with a liquid vaporization apparatusV.

Thermal energy is produced by means of the power plant 3, which may besupplied with a fuel 1, for example of coal or natural gas in the caseof a thermal power plant. In the case of a thermal power plant, thelatter produces gases, at least a proportion of which is used for thevaporization of water or the heating of water vapor. Accordingly, thethermal power plant produces water vapor 5.

The power plant 3 may also be a nuclear power plant, in which thenuclear reaction heats and vaporizes water, whether directly orindirectly, to produce water vapor 5.

A proportion 13 of the water vapor 5, comprising at least 70% of theflow rate 5, is expanded in a first turbine T1, whereby the expandedsteam 19 is then generally condensed in a condenser C, then returned tothe power plant 3, and the first turbine is used to drive an electricitygenerator G1 for the production of electricity.

The remaining water vapor 9, comprising no more than 30% of the flowrate 5, is used to heat a vaporized cryogenic liquid 17, which may befor example air or nitrogen. The vaporized liquid 17 is heated by thewater vapor in the heat-exchanger E to a temperature which exceeds theambient temperature, and delivered to the second turbine T2. The secondturbine is used to drive an electricity generator G2. If the expansionof the vaporized liquid 17 proceeds in a number of steps, the vaporizedliquid 17 may be heated in advance of each step.

This represents the simplest form of embodiment of the invention. Inthis case, the air or nitrogen expanded in the second turbine T2 may bedischarged to the atmosphere. The water vapor 9 which has heated the gas17 in the heat-exchanger E may be returned to the power plant 3, whereapplicable after condensation in a condenser, which may be the same asthat used down-circuit of the turbine T1 (the condenser C), ordischarged to the atmosphere.

The quantity of electricity produced by the two generators G1, G2exceeds that which would be produced if all the steam 5 were deliveredto the first turbine T1, and only generator G1 were in service.

The integrated method employs mechanical or electrical energy 7originating from the power plant 3 for the operation of an apparatus Lfor the liquefaction of an atmospheric gas, for example air or nitrogen.The liquefied gas is stored in a storage facility S, and the storedliquid is tapped for vaporization in the vaporizer V, in order to supplythe gas to be expanded in the second turbine T2.

The liquefied gas may be a gas other than an atmospheric gas, forexample natural gas or carbon dioxide.

Preferably, during a first period, the liquefaction apparatus L is notin service, and the stored liquid is vaporized, heated by the steam 9and delivered to the second turbine T2. This period corresponds to aperiod of higher electricity demand and/or a period in which theelectricity tariff is higher. Only a proportion 13 of the steam isdelivered to the first turbine T1. The proportion 13 constitutes atleast 70% of the flow rate 5.

During a second period, which is a period of lower electricity demandand/or a period in which the electricity tariff is lower than in thefirst period, the full amount of steam 5 is delivered to the firstturbine T1, constituting the flow rate 13, the liquefaction apparatusreceives energy 7 for the liquefaction of gas and stores the liquefiedgas. The vaporizer V and the turbine T2 are not in service. Noproportion of the steam is delivered to the heat-exchanger E.

A further possibility, if the power plant 3 is a thermal power plant,would be the employment of a proportion of the gases to heat the gas 17in the heat-exchanger E, and of the remainder of the gases to heat thewater vapor or water, in order to generate steam for delivery to thefirst turbine T1. The proportion of the gases delivered to theheat-exchanger E will be limited to no more than 30% of the total flowrate, in order to permit the continuing operation of the turbine T1.

Rather than dividing the water vapor 5 in two for the supply of theturbine T1 and the heat-exchanger E, another possibility would be tofeed the water vapor 5 into the heat-exchanger E first, prior to theexpansion of the water vapor in the first turbine T1.

Likewise in a thermal power plant, the gases might firstly be fed to theheat-exchanger E for the heating of the gas 17, then used to heat thewater vapor to be delivered to the first turbine T1.

The water vapor 9 for the heating of the heat-exchanger E may originatefrom an inter-stage in the first turbine T1.

As illustrated in FIG. 2, a number of streams of water vapor atdifferent temperatures may be used to heat the vaporized liquid 17 atdifferent stages.

In order to improve heat exchange efficiency, the turbine T1 in FIG. 1is comprised of a high-pressure turbine T1′, an intermediate-pressureturbine T1″ and a low-pressure turbine T1′″. The water vapor 13 isexpanded in these three turbines in series, and the steam is tapped ateight different pressure levels. Each of these streams of steam heatsthe vaporized liquid 17 in a heat-exchanger E1, E2, E3, E4, E5, E6, E7,E8 to produce the heated stream delivered to the turbine T2. Theheat-exchangers E1, E2, E3, E4, E5, E6, E7, E8 fulfil the role of E inFIG. 1. Likewise, the turbine T2 may be comprised of a number ofexpansion stages, with reheating prior to each expansion, in accordancewith the principle described above. The streams of steam are combinedagain and delivered to the condenser C, where the steam 19 dischargedfrom the final turbine T1′″ is condensed. As illustrated in FIG. 1, thesteam condensed in the condenser C may be transmitted to the power plant3.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims. The presentinvention may suitably comprise, consist or consist essentially of theelements disclosed and may be practiced in the absence of an element notdisclosed. Furthermore, if there is language referring to order, such asfirst and second, it should be understood in an exemplary sense and notin a limiting sense. For example, it can be recognized by those skilledin the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means thesubsequently identified claim elements are a nonexclusive listing (i.e.,anything else may be additionally included and remain within the scopeof “comprising”). “Comprising” as used herein may be replaced by themore limited transitional terms “consisting essentially of” and“consisting of” unless otherwise indicated herein.

“Providing” in a claim is defined to mean furnishing, supplying, makingavailable, or preparing something. The step may be performed by anyactor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event orcircumstances may or may not occur. The description includes instanceswhere the event or circumstance occurs and instances where it does notoccur.

Ranges may be expressed herein as from about one particular value,and/or to about another particular value. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value and/or to the other particular value, along withall combinations within said range.

All references identified herein are each hereby incorporated byreference into this application in their entireties, as well as for thespecific information for which each is cited.

1-14. (canceled)
 15. A method for the generation of electricity and thestorage of energy by means of a thermal power plant or a nuclear powerplant, and a liquid vaporization apparatus, wherein the method comprisesthe steps of: A) during a first period: a) producing thermal energy by apower plant selected from the group consisting of the thermal powerplant and the nuclear power plant, wherein the produced thermal energyis used to vaporize water or to heat water vapor, which is then expandedin a first turbine, and the first turbine is used to drive anelectricity generator for the production of electricity; b) vaporizingliquefied gas sourced from a cryogenic storage facility to produce apressurized gas; c) heating the pressurized gas d) expanding thepressurized fluid in a second turbine for the production of electricity;and e) heating the pressurized fluid, wherein a proportion of thethermal energy produced in step a) is used for the heating of thepressurized fluid, by employing a proportion of the gases from thethermal power plant or a proportion of the water vapor to be deliveredto the first turbine of the thermal or nuclear power plant, or aproportion of the heat of the water vapor to be delivered to the firstturbine of the thermal or nuclear power plant for the heating of thepressurized fluid; B) during a second period: a′) producing thermalenergy by means of the thermal or nuclear power plant, and using thethermal energy to generate electricity; b′) using electrical and/ormechanical energy generated by the power plant to liquefy the gas; andc′) storing the liquefied gas in a storage facility.
 16. The method asclaimed in claim 15, wherein thermal energy is produced by means of anuclear power plant, a fluid is heated by the heat generated by anuclear reaction, a proportion of the heat energy of the heated fluid isused to preheat the fluid to be delivered to the second turbine, and afurther proportion of the heat energy of the heated fluid is used toheat the water or water vapor delivered to the first turbine, where itsexpansion generates electricity.
 17. The method as claimed in claim 16,wherein a first proportion of the fluid heated by the nuclear reactionheats the water or water vapor to be delivered to the first turbine, anda second proportion of the fluid heated by the nuclear reaction heatsthe pressurized gas to be delivered to the second turbine, whereby theflow rate of the second proportion of the fluid is no more than 30% ofthe sum of the first and second proportions.
 18. The method as claimedin claim 16, wherein a first proportion of the water vapor generated bythe nuclear reaction expands in the first turbine and a secondproportion of the water vapor generated by the nuclear reaction is usedto preheat the pressurized gas to be delivered to the second turbine,whereby the flow rate of the second proportion of the water vapor is nomore than 30% of the sum of the first and second proportions.
 19. Themethod as claimed in claim 15, wherein thermal energy is produced bymeans of a thermal power plant, gases are produced by the combustion ofa fuel, a proportion of the heat of the gases is used to preheat thefluid to be delivered to the second turbine, and a further proportion ofthe heat of the gases is used to heat the water or water vapor deliveredto a first turbine, where its expansion generates electricity.
 20. Themethod as claimed in claim 19, The method as claimed in claim 19,wherein a first proportion of the gases is used to heat the steamdelivered to the first turbine for expansion, and a second proportion ofthe gases preheats the pressurized gas, whereby the flow rate of thesecond proportion of the gases is no more than 30% of the sum of thefirst and second proportions.
 21. The method as claimed in claim 19,wherein the gases firstly heat the pressurized gas, and are then used toheat the steam which is delivered to the first turbine for expansion.22. The method as claimed in claim 15, wherein the first and secondturbines in combination produce more electricity than would have beenproduced by the first turbine alone, using all the heat energy of theheated fluid or the gases respectively to heat the water or water vaporto be delivered to the first turbine.
 23. The method as claimed in claim15, wherein the only gas which expands in the second turbine is thepressurized fluid.
 24. The method as claimed in claim 15, wherein thesecond period corresponds to a period of lower electricity demand and/ora period in which the electricity tariff is lower than in the firstperiod.
 25. The method as claimed in claim 15, wherein, during thesecond period, the first turbine generates electricity, which is used toliquefy the gas.
 26. The method as claimed in claim 15, wherein, duringthe first period, the gas is not liquefied.
 27. The method as claimed inclaim 15, wherein, during the first period, the stored liquid is notvaporized and/or the pressurized fluid is not expanded in the secondturbine.
 28. An integrated electricity generating and energy storageapparatus, comprising a power plant selected from the group consistingof a nuclear power plant or a thermal power plant, the power planthaving: a first turbine, which is a steam turbine, connected to meansfor the generation of electricity; a liquefaction apparatus configuredto liquefy a gas; a vaporization apparatus configured to vaporize aliquefied gas originating from the liquefaction apparatus to form avaporized liquefied gas; a second turbine disposed downstream and influid communication with the vaporization apparatus, the second turbinebeing connected to a means for the generation of electricity, the secondturbine being configured to receive the vaporized liquefied gasoriginating from the vaporization apparatus and expand the vaporizedliquefied gas; means for the transference of electrical or mechanicalenergy from the power plant to the liquefaction apparatus; means for thepreheating of the vaporized liquefied gas upstream of the secondturbine; means for the transmission: i) of the gases or water vapor,originating from the thermal power plant, or ii) of the water vaporgenerated and/or heated by the nuclear reaction, and originating fromthe nuclear power plant, or iii) of a fluid heated by the nuclearreaction, originating from the nuclear power plant, to the means for thepreheating of the vaporized liquefied gas, wherein the liquefactionapparatus is connected to the power plant for the supply thereto ofelectrical and/or mechanical energy generated by the power plant; and astorage facility for the storage of liquefied gas.